The companies have promised that they are working to protect their businesses from improper efforts to influence US voters.

Earlier this week, Facebook said it had taken down 652 pages, accounts and groups that it identified as part of coordinated disinformation campaigns that had ties to foreign countries, including Iran and Russia.

And Microsoft this week announced what it called a “Defending Democracy program” to offer protections to candidates and related organizations.

BuzzFeed reported that Facebook’s head of cybersecurity policy, Nathaniel Gleicher, invited employees from a dozen companies to the meeting, at Twitter’s headquarters in downtown San Francisco.

Nine of the companies met at Facebook headquarters in May, with officials from the Department of Homeland Security and the FBI, BuzzFeed reported.

Twitter declined comment. Spokespeople for Facebook, Google and Microsoft did not immediately respond to requests for comment on the meeting.